A conventional stacking apparatus 10 is illustrated in FIG. 1. The stacking apparatus 10 is configured for use adjacent to a rotary die cut machine 12 which cuts blanks (not illustrated) from sheets of material, for example, corrugated paperboard. The stacking apparatus 10 includes a receiving or “layboy” section 14 that receives the blanks from the die cut machine 12 and discharges them onto a transfer conveyor 16. The transfer conveyor 16 carries the blanks to an inclined main conveyor 18, and the blanks travel along the main conveyor 18 to its downstream end 20 where they are discharged into a accumulator 22 (sometimes referred to as a “hopper”).
Die cut machines produce a certain amount of scrap material during operation which consists mainly of the portions of the input material that do not become part of a finished blank. In addition, each blank may include slots or through-openings. The material cut from the blanks to form these slots and through-openings also constitutes scrap.
Most scrap material produced by the die cut machine drops beneath or immediately in front of the die cut machine as it operates. However, it is not uncommon for a material sheet to be cut incompletely so that portions of the sheet that were supposed to be removed wind up traveling into the layboy with the blank. Excessive scrap in the transport path between the layboy section and the final stack of blanks may adversely affect the transport of the blanks. That is, the scrap may interfere with the alignment of the blanks or lead to jams. Alternately, if the scrap is carried all the way through the stacker and into the final stack of blanks, the blanks in the stack will have gaps therebetween where the scrap material is present thus resulting in a crooked, or oversized or non-uniform stack of blanks. Some scrap may even end up inside a finished box formed from the cut blanks; this is generally undesirable to most end customers and must be completely avoided in some applications, such as boxes for use to package food.
It is therefore known to provide various scrap removal devices in a layboy. These may comprise, for example, brushes that gently contact a top and/or bottom surface of the moving blanks to dislodge the scrap. It would be desirable to further reduce the presence of scrap in a stream of sheets being conveyed in a sheet stacking system.